1. Field of the Invention
The present invention relates to a device and method for controlling radio-frequency power in a wireless terminal. More particularly, the present invention relates to a device and method for controlling radio-frequency power in a wireless terminal, by which radio-frequency power transmitted from the wireless terminal to a base station is flexibly controlled and transmitted.
2. Description of the Related Art
Generally, in radio-frequency (RF) power control in a wireless terminal, the wireless terminal transmits to a base station constant RF power corresponding to its power control level (PCL) based on a power control command that is determined and given by the base station. Here, the power difference between respective power levels is about 2 dB per level, and has a tolerance of about maximum ±3 dB per level according to “tolerance for condition” allowed by 3GPP TS 45.005.
When a user makes a call or data communication by using a wireless terminal in a base station network, a base station monitors service quality in real-time, and sends a command to instruct the wireless terminal to level RF power transmitted to the base station up by 1˜4 levels or down by 1˜2 levels.
For example, when the wireless terminal which is making a call at PCL 8 (a default value: 27 dBm) moves far away from a corresponding base station or when an Rx quality becomes degraded due to occurrence of an obstacle between antennas of the base station and the wireless terminal, the base station sends a command to the wireless terminal to level up an existing power level by three levels so as to have PCL 5 (a default value: 33 dBm) and to transmit (Tx) it. At this time, however, if an Rx quality sufficient to have transmission power of only about 31.5 dBm can in fact be secured in an electrical field of a region where the wireless terminal is located, the wireless terminal may use power by about 1.5 dBm more than it needs. The power difference of 1.5 dB at PCL 5 corresponds to an amount that can improve current consumption of about 20 mA and a surface absorption rate (SAR) of 0.4 mW/g. Since RF power corresponding to respective RF power control levels is designated, if the base station sends a command to provide PCL 5, the wireless terminal must unconditionally transmit RF power of 33 dBm corresponding thereto. Then, in the case where 31.5 dBm is preset from the outset, when the wireless terminal is located in an electrical field lower than the above case, i.e., when an Rx quality can be secured only when RF power of 33 dBm has to be transmitted, there may occur a severe mute effect or a data communication error that a message breakage occurs during a call because a target Rx quality is not secured.
Thus, there is a problem in that even at the same PCL, more power than needed increases the current consumption of the wireless terminal to thereby shorten the lifetime of a battery and to increase an SAR.